A Slippery Solution To A Sticky Problem

By infusing porous surfaces with slippery liquids, researchers have developed a way to prevent mussel adhesion, a key contributor to marine biofouling of ship hulls.

AsianScientist (Aug. 20, 2017) – In a study published in Science, a team of researchers from Singapore and the US have used a lubricant-infused coating to prevent the adhesion of marine organisms such as mussels to surfaces.

The accumulation of biological organisms on wet surfaces is known as biofouling, and it is especially rampant in the shipping industry where marine organisms such as mussels and barnacles adhere to the hulls of ships. Marine biofouling increases the weight of the ship, thus increasing the ship’s fuel consumption and leading to significant economic cost. Additionally, marine biofouling contributes to the spread of invasive species when ships transit from one port to another.

To counter this problem, antifouling agents have been developed to reduce the extent of biofouling. These agents fall into two broad categories: one type of antifouling agent is resin embedded with copper, but these are toxic to the environment; the second type are low surface energy polymers, like Teflon, which are expensive to produce. However, current antifouling agents do not prevent adhesion by marine organisms but only make biofoulers easier to remove.

In this study, the scientists used a 3D polydimethylsiloxane infused with silicone oil (i-PDMS) to coat surfaces and found that they prevented the Asian green mussel, Perna viridis, from attaching to coated surfaces.

“This technology was developed by our collaborators at Harvard University and is called SLIPS, which stands for ‘slippery liquid infused porous surface,’” Associate Professor Ali Miserez from Nanyang Technological University, Singapore, told Asian Scientist Magazine.

“Basically, you have a solid surface on which you apply a lubricant that does not disperse in water. The technology was inspired by the pitcher plant—insects enter the pitcher plant and slip in because the inside surface of the plant contains a natural lubricant.”

When researchers tested the i-PDMS with mussels which typically adhere non-discriminately to surfaces using protein-based adhesive threads, they found that the mussels did not attach to i-PDMS-coated surfaces. To understand why i-PDMS prevented mussel adhesion, the team measured the nanoscale contact forces between the mussels’ ‘feet’ and the surfaces being probed. They found that i-PDMS interferes with the ability of the mussel to sense the coated surface.

“There is a specific protein inside the mussels’ feet—a mechanosensor—that they use to sense surfaces. When the feet contact the i-PDMS-coated surface, a capillary bridge forms and there’s a very tiny force that pulls on the feet, confusing the mussels so they don’t secrete the adhesive threads as they would usually do,” said Miserez.

The antifouling capacity of i-PDMS was so great that one challenge Miserez and his colleagues faced was a lack of data points for measurements of contact forces.

“We were measuring how much force was required to detach mussels from the surface, but the mussels were barely laying down adhesion threads on i-PDMS-coated surfaces, so for statistical significance we had to repeat the experiment many times,” said Miserez.

Having demonstrated and understood the impressive antifouling capabilities of i-PDMS, the researchers are looking to produce the coating at a commercial scale. They are also tweaking the formulation of the coating material for various other industrial applications, such as the prevention of bacterial biofilm formation in aquaculture.

The article can be found at: Amini et al. (2017) Preventing Mussel Adhesion Using Lubricant-Infused Materials.


Copyright: Asian Scientist Magazine; Photo: Larry J. Friesen.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Jeremy received his PhD from Nanyang Technological University, Singapore, where he studied the role of the tumor microenvironment in cancer progression.

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